Method and device for testing drive parameters of an electropneumatic valve for a pneumatic actuating drive

Abstract

A method and an electronic device are disclosed for testing drive parameters of an electropneumatic valve which is inserted into a closed control loop for position regulation of a switching element of a pneumatic actuating drive for a fitting which can be operated thereby. The electropneumatic valve can be driven by an alternating signal of a specific amplitude, such that the control loop will oscillate about a nominal position value to be regulated by alternate ventilation and venting of the valve, such that hysteresis present in the pneumatic actuating drive can be overcome. The trajectory of the position oscillation that is produced can, at the same time, be detected at the switching element using sensors, from which a characteristic of the control loop for the selected amplitude can be determined to confirm whether an opening point which is suitable for the control loop has been found.

What is claimed is: 
     
       1. A method for testing drive parameters of an electropneumatic valve in a closed control loop for position regulation of a switching element of a pneumatic actuating drive for a fitting, the method comprising:
 driving an electropneumatic valve by an alternating signal of a selected amplitude, such that the control loop is regulated to oscillate about a nominal position value by alternate ventilation and venting of the valve to address hysteresis in the pneumatic actuating drive; 
 detecting a trajectory of a position oscillation which is produced at the switching element via sensors; and 
 determining a characteristic of the control loop for the selected amplitude to confirm a desired opening point for the control loop. 
 
     
     
       2. The method as claimed in  claim 1 , comprising:
 forming a mean value over a plurality of recorded oscillation periods of the switching element. 
 
     
     
       3. The method as claimed in  claim 2 , comprising:
 ignoring a result of a first oscillation when forming the mean value. 
 
     
     
       4. The method as claimed in  claim 1 , comprising:
 separately determining drive parameters for ventilation and venting of the valve to produce the position oscillation. 
 
     
     
       5. The method as claimed in  claim 1 , comprising:
 defining a position point at which the switching element cannot approach more slowly than a defined maximum permissible time, but not more quickly than a defined minimum permissible time, as the desired opening point for the position regulation. 
 
     
     
       6. The method as claimed in  claim 1 , comprising:
 measuring a time to overcome the hysteresis of the pneumatic actuating drive at a predetermined drive level for the position oscillation of the switching element. 
 
     
     
       7. The device as claimed in  claim 1 , wherein the electropneumatic valve comprises:
 a 3/3 switching function for switch positions of ventilation, closed position and venting. 
 
     
     
       8. A computer readable medium for storing a computer program to cause an electronic device to perform the steps of:
 driving an electropneumatic valve by an alternating signal of a selected amplitude, such that the control loop is regulated to oscillate about a nominal position value by alternate ventilation and venting of the valve to address hysteresis in the pneumatic actuating drive; 
 detecting a trajectory of a position oscillation which is produced at the switching element via sensors; and 
 determining a characteristic of the control loop for the selected amplitude to confirm a desired opening point for the control loop. 
 
     
     
       9. The computer readable medium as claimed in  claim 8 , wherein a routine for determining the regulation characteristic is implemented by appropriate control commands stored in software. 
     
     
       10. The method as claimed in  claim 1 , comprising:
 supplying the detected trajectory of the position oscillation to an input side of a regulation unit, which determines the characteristic of the control loop. 
 
     
     
       11. The method as claimed in  claim 10 , wherein determining the characteristic of the control loop comprises:
 evaluating a time interval between driving the electromagnetic valve and the detected trajectory of the position oscillation. 
 
     
     
       12. The method as claimed in  claim 1 , wherein detecting the trajectory of the position oscillation identifies a reaction of the switching element. 
     
     
       13. The method as claimed in  claim 1 , comprising:
 varying the selected amplitude of the alternating signal based on the determined characteristic. 
 
     
     
       14. The computer readable medium as claimed in  claim 8 , wherein the method preformed by the electronic device comprises:
 supplying the detected trajectory of the position oscillation to an input side of a regulation unit, which determines the characteristic of the control loop. 
 
     
     
       15. The computer readable medium as claimed in  claim 8 , wherein determining the characteristic of the control loop comprises:
 evaluating a time interval between driving the electromagnetic valve and the detected trajectory of the position oscillation. 
 
     
     
       16. The method as claimed in  claim 1 , wherein the method preformed by the electronic device comprises:
 detecting the trajectory of the position oscillation identifies a reaction of the switching element. 
 
     
     
       17. The method as claimed in  claim 1 , wherein the method performed by the electronic device comprises:
 varying the selected amplitude of the alternating signal based on the determined characteristic.